A greater force is required to drive a wood screw while screwing harder wood. Besides, the wood debris generated during screwing is usually exhausted out ineffectively and incompletely, likely to accumulate inside the wood and squeeze mutually, which may cause the wood to crack.
A Taiwan patent No. M491743 disclosed a wood screw, which comprises a screw head and at least one first thread, and a screw shank. The screw shank includes a parallel portion, a tapered portion growing thinner gradually, a tip formed on the terminal of the tapered portion. A pattern is formed on the tapered portion, enabling the user to drive the wood screw into wood without drilling a hole beforehand, preventing wood from cracking, and reducing screwing torque.
However, the pattern of the conventional wood screw consists of irregular protrusions, which may result in uneven biting force between the wood screw and the workpiece and cause insecure fixing and shaking. Besides, the pattern does not have debris exhaust structure. Thus, wood debris may accumulate between the pattern and the workpiece and cause cracks during screwing. Therefore, the conventional technology still has room to improve.